Purkeys Liftgate Double Check User manual

A MISSION CRITICAL ELECTRONICS BRAN
D
LIFTGATE CHARGING SYSTEM
DOUBLE CHECK™
USER GUIDE
INST056 R4.00

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CONTENTS
General Information ..........................................................................................2
Double Check Diagram.....................................................................................4
20 Amp Applied Load Tester Diagram............................................................4
Operating Instructions ......................................................................................5
Connecting to Power Source...................................................................5
Testing the Power Source.........................................................................6
Testing the 7-Way Cable ..........................................................................9
Testing the Ligate Charging System...................................................10
Testing the DC/DC Converter in the Battery Box .............................13
DC/DC Converter Information & Diagnostics ..................................15
Double Check Test Cart: Optional (Example)..............................................17
Double Check Troubleshooting Summary ...................................................19
Tractor without 7-way............................................................................19
Tractor with 7-way..................................................................................20
Testing the Ligate Charging System...................................................21
Testing the DC/DC Converter ..............................................................22
Part List..............................................................................................................23
Limited Commercial Warranty Policy...........................................................28

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e Purkeys Ligate Charging System Double Check™ (Double Check) is
a tool used to test, troubleshoot, or diagnose problems in both the power
source (i.e. tractor) and the ligate charging system on the trailer itself (i.e.
Purkeys Direct™ and Select™ ligate charging systems).
is system is user-friendly and will allow you to use any available vehicle
as a power source. With it, you can test the entire system from tractor to
DC/DC converter in approximately 15 minutes.
Once a proper power source is established, it is simple to test the ligate
charging system. e Double Check tool comes in a case that contains all
the components and adapters you will need to test your trucks/trailers, with
the exception of a multimeter and amp clamp, which your shop should
have.
Here are pictures and descriptions of the most crucial parts and adapters
you will need to test your system:
GENERAL INFORMATION
Ligate Double Check display box 20 amp applied load
Input adapter with alligator clips
(connects to power source)
Input adapter for the 7-way
(connects to power source)

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LIFTGATE DOUBLE CHECK USER GUIDE
7-way output adapterDC/DC inverter harness
Multimeter, leads, and amp clamp: NOT included in kit

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DOUBLE CHECK DIAGRAM
20 AMP APPLIED LOAD TESTER DIAGRAM

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LIFTGATE DOUBLE CHECK USER GUIDE
OPERATING INSTRUCTIONS
e Double Check can use any available vehicle as a power source (i.e. car,
tractor), as long as the vehicle has a 12 V battery and an alternator. However,
if a tractor is being used as the source, it is critical that you ensure that no
part of the tractor is touching the trailer—it cannot be coupled with, or even
touching, the trailer—as the 5th wheel ground path will cause inaccurate test
results.
CONNECTING TO THE POWER SOURCE
Table 1: 20 Amp Applied Load Tester LED Status
LED STATUS
Solid Green Applied Load is ready to test power source
Solid Red Source is being tested
Blinking Red Applied Load is resetting
e 20 Amp Applied Load Tester is used to test the power source. It is crucial
to test the source while under a load to ensure it can provide the proper
voltage needed. Do not assume the vehicle is an adequate source, as a faulty
source may cause a misdiagnosis of the ligate charging system due to an
inadequate power source.
When using the 20 Amp Applied Load, connect the tool to the Double Check
and the power source and make sure the vehicle is running. e Test Status
LED on the 20 Amp Applied Load Tester will turn on. See Table 1 for LED
indications.

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Step 1: Select a vehicle to be used as
the power source and determine
the appropriate input adapter:
• Battery input adapter
• 7-way adapter (if testing with a
7-way cord, see section Testing
the Source Vehicle with a
7-Way Cord)
• Dual pole adapter
• Dual pole female adapter
• Single pole adapter
• Single pole female adapter
Step 2: Connect the 20 Amp Load
Tester to the output side of the
Double Check test display box.
TESTING THE POWER SOURCE
Step 3: Connect the multimeter
leads to the ports on the bottom of
the Double Check test display box
and to your multimeter.

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LIFTGATE DOUBLE CHECK USER GUIDE
Step 4: Connect the 7-way input
adapter to the Double Check to
test the power source (i.e. tractor).
Step 5: Move to the rear of the
tractor and remove the 7-way
cable from the receptacle and plug
the 7-way input adapter into the
tractor.
Step 6: Aer connecting the adapter,
turn the multimeter to “VOLTS
DC” and start the tractor. If the
tractor is functioning correctly, the
large LED on the 20 amp applied
load test box will illuminate solid
green and the voltmeter should
read above 13.2 volts. Record the
voltage.
IMPORTANT NOTE: If the large LED on the test box is not solid green, or if
the voltmeter reads below 13.2 volts, the voltage output is not sucient and
further tractor diagnosis is required.

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Step 7: Press the START button on
the 20 amp applied load test box.
e display box LED will be solid
red to show there is a 20 amp draw
on the tractor and the voltmeter
should read higher than 12.0 volts.
Record the loaded voltage.
IMPORTANT NOTE: If the voltmeter reads below 12.0 volts, the power
source is not sucient and further tractor diagnosis is required.
Step 8: If the tractor has passed up to this point, move on to the next test.

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LIFTGATE DOUBLE CHECK USER GUIDE
TESTING THE 7-WAY CABLE
e next step is to test the 7-way cable by pulling a 20 amp load through
the 7-way and tractor to prove that sucient current can pass through the
tractor’s 7-way cable to the trailer.
Step 1: Remove the 7-way adapter
from the tractor, plug the 7-way
cord back into the tractor’s
receptacle, and connect the other
end of the 7-way cord into the
Double Check test box adapter
receptacle.
Step 2: Start the tractor and record the unloaded voltage reading from the
voltmeter. If the tractor and 7-way are working correctly, you should see a
reading of 13.2 volts or higher.
If the large LED is not green, or if the voltmeter shows less than 13.2 volts,
check for a blown fuse in the tractor or proceed to the next step to test for a
faulty 7-way cord.
Step 3: Press the start button on the 20 amp load box and read the loaded
voltage on the voltmeter. If the voltmeter reads less than 11 volts while
loaded at 20 amp, the 7-way cable is bad.
If the 7-way cable has passed up to this point, then both the tractor and the
7-way cable are good.

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TESTING THE LIFTGATE CHARGING SYSTEM
e next step is to test the ligate charging system. is test will allow you to
isolate the failed component that is not allowing the batteries to charge.
Note that if the LEDs on the Direct or Select controller do not turn on, you
will need to check the 2 amp fuse located on the charging plate inside the
ligate battery box.
If the LEDs on the Direct or Select controller alternate between green and red,
there is insucient power from the power source vehicle or the wiring (the
previous tests will have identied any issues with this).
Step 1: Select the correct input
adapter for the power source
being used.
Step 2: e multimeter will also be
used during this test, so connect
the volt leads to the Double
Check.

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LIFTGATE DOUBLE CHECK USER GUIDE
Step 3: Connect the 7-way output
adapter from the Double Check to
the trailer nosebox receptacle.
NOTE: is test is not tractor dependent, but it MUST have an adequate
power source to test. Examples of acceptable power sources include:
• shop trucks,
• forklis,
• switchers,
• and/or test carts supported by a battery charger.
If a tractor is not going to be used as the power source for testing, you will use
the alligator clip input adapter shown below.
To supply power, the alligator clips of the input adapter are connected directly
to the battery of any running engine or battery charger supported test cart.
If you are using a battery charger on a test cart, it should be set at a 10 amp
charge.

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NOTE: You should now see a
reading on the Double Check’s
graduated scale of amps from 5-25
amps. e amperage displayed
will vary based on the state of
the ligate batteries. With fully-
charged batteries, the DC/DC
inverter only requires a few amps
to maintain the batteries. In the
case the batteries are low or weak,
the DC/DC converter requires
much greater amperage as it tries
to bring the batteries up to full
charge.
Once the trailer is connected and
the system is loaded, the voltmeter
should read above 11 volts.
IMPORTANT: If the red AMPS LEDs show no current ow, and the
voltmeter is BELOW 11 volts, you have an issue with the power source.
If the LEDs show no current ow, but the voltmeter shows ABOVE 11 volts,
there is an issue in the trailer charging system and you should refer to the
appropriate trouble tree at the end of this guide.
Step 4: If the battery voltage is slowly increasing up to 13.2 volts as the
amps commanded from the converter are decreasing, then the system is
functioning properly and no further investigation is needed.
If the batteries are fully charged and only 5 amps or less are being
commanded from the converter, you can cycle the ligate one or two times
while watching the Double Check and voltmeter to ensure that the system
is topping the batteries back o.
If no current ow is seen, and you have proper source power, make sure all
fuses are intact. is includes the 30 amp fuses in the indicator box on the
nose of the trailer and the 2 amp fuse in the battery box. If all fuses are
in good working order, continue to the next step of testing the DC/DC
converter.
IMPORTANT: is test does not replace a battery load test. You should still
inspect and test batteries as needed or on a PM level.

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LIFTGATE DOUBLE CHECK USER GUIDE
is step is not required unless a fault was found. If no current ow was
observed during the previous test, and all fuses are in good working order,
you will now isolate and test the DC/DC converter.
Step 1: Connect the alligator clip
input adapter and the DC/DC
converter adapter harness to the
Double Check. (e end with the
alligator clips and male connector
will connect to the battery box
and the long end of the adapter
connects to the Double Check).
Step 2: Connect the alligator clips input adapter to any of the previously
described power sources.
Step 3: Connect the alligator clips on
the output harness to the ligate
batteries.
Unplug the DC/DC converter plug
and, in its place, connect the
adapter harness to the inverter.
In the example picture, we have
connected the ground clamp to the
ground stud inside the battery box.
If this stud does not provide an
ample ground, it may be necessary
to adjust the converter mounting
plate inside the box so the ground
clamp can be attached to the
negative terminal on the battery.
e green light on the converter should be illuminated. On the Double Check
and voltmeter, you should see an AMPS reading in relation to the state of
the batteries.
TESTING THE DC/DC CONVERTER IN THE BATTERY
BOX

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With the charger set to 10 amps, the voltage on the meter should continue to
increase as the amperage commanded by the DC/DC converter decreases.
If, like the previous step, the batteries are at or near full charge, operating
the ligate should trigger a response from the converter to command
higher amperage to top o the batteries.
In the event that you have a proper power source, but the converter is not
functioning, the converter has gone bad and should be replaced.
If the converter functions correctly during this test, but it was not functioning
correctly from the nosebox, there is an issue with the main harness or Aux
circuit that needs to be repaired/replaced.
Always ensure that all connections in the system are “tight and bright” to
minimize resistance. It is also important to repeat the test if the DC/DC
converter was replaced to ensure that the charging problems have been
xed and that the system is now functioning properly.

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LIFTGATE DOUBLE CHECK USER GUIDE
DC/DC CONVERTER INFORMATION & DIAGNOSTICS
e image below shows the LED lights on the DC/DC converter. A rapid
ashing red LED on the converter is normal if the trailer is disconnected from
a running truck. It will continue to ash for a short period of time. A rapid
ashing red LED is only a fault if the trailer is connected to a running truck.
LED STATUS CONDITION ACTION NEEDED
Solid Green DC/DC converter is
on.
Ensure circuit
protection on output
side is in working
order.
Rapid Flashing Red DC/DC converter
has a fault. Determine the fault.
No Light No voltage. Determine the fault.

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Note: It is possible to have a green light on a faulty converter; we have seen
this problem during check lane troubleshooting. e converter may be
properly supplied with power, but have insucient output, or none at all,
to charge the batteries. is can be observed while testing the converter
by noting the amperage being used to charge the batteries. In this case you
would see proper source voltage on the multimeter, but no current ow to
the batteries. If cycling the ligate has no eect on the amps being required
by the converter, then you have proven that the converter has failed. is
test should be replicated with the new converter to ensure it is functioning
properly. Furthermore, this second test conrms that the failed part was
properly isolated and replaced.

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LIFTGATE DOUBLE CHECK USER GUIDE
Although not required in order to use the Double Check, some shops prefer
to outt a test cart to support the use of the Double Check tool. It can make
the job of troubleshooting the system easier by providing a work space for
testing as well as eliminating the need to work from the ground or balanced
behind the tractor.
is section shows an example cart,
but the conguration may vary,
depending on the particular needs
of your shop. Some shops have
an extension harness and a power
supply harness that can be used with
the test cart. On this example cart,
the power supply harness is wired
into the cart.
Example 1: e power supply plug
is wired to the top tray of the test
cart for convenience.
DOUBLE CHECK TEST CART: OPTIONAL (EXAMPLE)

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Example 2: ese wires go to the top
tray to supply the Double Check
with source power.
Example 3: A compact battery
charger and a standard truck
battery are securely fastened to the
bottom shelf of the test cart. e
battery charger and power supply
connections are both connected
below the terminals, allowing the
use of gator clips, if needed.
Example 4: e connector in the
top tray of the test cart is used to
supply the Double Check tool with
source power.
Example 5: For this cart, the shop
made an extension harness (not
included) that is used with the
7-way input adapter, allowing it to
reach the Double Check tool set
up on the test cart.